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The increasing use of engineered nanoparticles (NPs) poses an emerging challenge to biological wastewater treatment. The long-term impact of CuNPs on anaerobic ammonium oxidation (anammox) process was firstly investigated in this study. The nitrogen removal capacity of anammox reactor was nearly deprived within 30days under the stress of 5.0mgL -1 CuNPs and the relative abundance of anammox bacteria (Ca. Kuenenia) was decreased from 29.59% to 17.53%. Meanwhile, copper resistance genes associated with the Cus, Cop and Pco systems were enriched to eliminate excess intracellular copper. After the withdrawal of CuNPs from the influent, the nitrogen removal capacity of anammox biomass recovered completely within 70days. Overall, anammox biomass showed susceptibility, resistance and resilience to the stress of CuNPs. Therefore, the potential impacts of ENPs on anammox-based processes should be of great concern., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Previous studies investigating the risk of engineered nanoparticles (NPs) to biological wastewater treatment have primarily tested NPs individually; however, limited data are available on the impact of NPs on the anaerobic ammonium oxidation (anammox) process. In this study, the toxicity of CuNPs on anammox granules was investigated individually and in combination with CuONPs or ZnONPs. Exposure to CuNPs at 5mgg -1 suspended solids (SS) decreased the anammox activity to 47.1±8.5%, increased the lactate dehydrogenase level to 110.5±3.4% and increased the extracellular N 2 H 4 concentration by 16-fold but did not cause oxidative stress. The presence of CuONPs or ZnONPs at 5mgg -1 SS did not significantly aggravate or alleviate the toxicity of the CuNPs; however, the introduction of EDTA or S 2- could attenuate the adverse effects of the CuNPs, CuONPs and ZnONPs on the anammox granules. EDTA captured Cu ions, whereas S 2- shielded and deactivated Cu ions and passivated CuNPs. Therefore, our results indicated that the toxicity of NPs was dependent on the amount of active metal reaching the anammox cells. Overall, the results of this study have filled knowledge gaps and provided insights into the combined toxicity of NPs on anammox biomass., (Copyright © 2017 Elsevier B.V. All rights reserved.)

To facilitate the application of partial nitritation (PN) - anaerobic ammonium oxidation process in nitrogen removal from livestock wastewater, the inhibition of roxithromycin (ROX) and Cu(II) on the PN sludge was examined using a respirometric method. The results showed that the IC50 of ROX and Cu(II) on PN sludge were 346 and 74.3mgL(-1), respectively. The relative specific respiration rate (SRR) of ammonia-oxidizing bacteria (AOB) decreased from 87.4% to 17.7% with the ROX concentration increased from 0 to 500mgL(-1). When the concentration of Cu(II) increased from 0 to 160mgL(-1), the SRRs of AOB and nitrite-oxidizing bacteria decreased by 85.5% and 11.2%, respectively. According to the isobole plots analysis, combined suppression by ROX and Cu(II) was synergistic. Fourier transform infrared spectroscopy analyses showed that ROX exposure altered the positions of CO bonds, and the intensity of the absorption peak at 2100cm(-1) changed under Cu(II) exposure., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The increasing application of engineered nanoparticles (NPs) has posed an emerging challenge to wastewater treatment processes. The short-term impacts of CuNPs, CuONPs, ZnONPs and AgNPs on anaerobic ammonium oxidation (anammox) process were investigated firstly in this study. CuONPs, ZnONPs and AgNPs up to 50 mg g −1 suspended solid (SS) did not affect anammox activity, reactive oxygen species (ROS) production or cell membrane integrity. However, 1.25 mg g −1 SS CuNPs significantly inhibited the anammox activity and the loads that caused 50% inhibition were 4.64 ± 1.24 and 3.27 ± 0.79 mg g −1 SS for anammox granules and flocs, respectively. 5 mg g −1 SS CuNPs caused serious accumulation of the toxic intermediate N 2 H 4 . Furthermore, CuNPs interacted with extracellular polymeric substances by specifically bonding to tyrosine or tryptophan-containing groups, C-O-C in polysaccharides and –OH in polymeric compounds. Therefore, this study calls for more attention to the risks of NPs to the anammox-based processes. [ABSTRACT FROM AUTHOR]

The increasing use of engineered nanoparticles (NPs) poses an emerging challenge to biological wastewater treatment. The long-term impact of CuNPs on anaerobic ammonium oxidation (anammox) process was firstly investigated in this study. The nitrogen removal capacity of anammox reactor was nearly deprived within 30 days under the stress of 5.0 mg L −1 CuNPs and the relative abundance of anammox bacteria (Ca. Kuenenia ) was decreased from 29.59% to 17.53%. Meanwhile, copper resistance genes associated with the Cus, Cop and Pco systems were enriched to eliminate excess intracellular copper. After the withdrawal of CuNPs from the influent, the nitrogen removal capacity of anammox biomass recovered completely within 70 days. Overall, anammox biomass showed susceptibility, resistance and resilience to the stress of CuNPs. Therefore, the potential impacts of ENPs on anammox-based processes should be of great concern. [ABSTRACT FROM AUTHOR]